It includes a pic of a LARGE rattler that, according to him, took THREE shots from a Judge to kill it.

That doesn't come as a surprise to me in the least.
I used to carry a two shot .22 derringer in my jacket pocket loaded with one shot shell and one CB cap.
Every year in the Spring, when the grass grew real long, real fast, i was forever hitting snakes w/the tractor when mowing the grass.
All nonpoisonous of course since we don't have that kind in our yards here in NE Ohio - that I or the DNR is aware of anyhow..mostly garter snakes I believe, usually a foot to two long.

They'd come out of the mower in bad shape, but, still alive.

I'd "pop" them in the head with a shot shell first to slow them down, then finish them off with a CB cap. I don't recall how many I've sent to snake heaven over the years - maybe a dozen or two.
I do recall that all of them took a solid to the head to end things. The shot shells just slowed them down.

Snakes are tough.

Sad footnote...
Local laws changed and now it's illegal to humanely put down an injured creature.
Now I have to hack them up with a machete. It's pretty gross and I hate having to do it that way...